Einsteinium(III) oxide

Einsteinium(III) oxide is an oxide of the synthetic actinide einsteinium which has the molecular formula Es₂O₃. It is a colourless solid.^[1]

Einsteinium(III) oxide

__ Es3+     __ O2−
Names
IUPAC names Einsteinium sesquioxide Dieinsteinium trioxide Einsteinium(III) oxide
Identifiers
CAS Number	37362-94-0
ChemSpider	154325 deprecated
PubChem CID	177221 charge imbalance
Properties
Chemical formula	Es2O3
Molar mass	554 g/mol (253Es)
Appearance	colourless solid[1]
Structure
Crystal structure	Hexagonal
Space group	Ia3
Lattice constant	a = 370 pm, c = 600 pm[2]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Three modifications are known. The body-centered cubic form has lattice parameter a = 1076.6 ± 0.6 pm; this allows the ionic radius of the Es³⁺ ion to be calculated as 92.8 pm.^[3] The other two forms are monoclinic and hexagonal: the hexagonal form has the lanthanum(III) oxide structure.^[4]

Einsteinium(III) oxide can be obtained by annealing einsteinium(III) nitrate in sub-microgram quantities.^[3]